The home side lost openers Mark Pettini and Tom Westley in successive deliveries to slip to 12-2 in reply.

Jesse Ryder smashed 90 to keep Essex in it, but Oliver Hannon-Dalby (4-44) had the New Zealander caught and then saw off the tail as the hosts made 204.

The Bears maintain their hold on Essex

Warwickshire have now won eight of their nine away List A games against Essex, the most recent of which was in 2007.

The Bear also won at Chelmsford in the T20 quarter-finals just three weeks ago, when they were also skippered by the county vice-captain, former Essex opener Varun Chopra

The margin of victory had looked likely to be even bigger when Essex stumbled to 106-5, only Ravi Bopara (20) offering any real resistance.

But Ryder smashed three sixes and seven fours in his 95-ball innings, keeping hopes of an unlikely victory alive before being caught by Warwickshire captain Varun Chopra, playing against his old club.

Hannon-Dalby, impressive in the Bears' T20 Blast final win over Lancashire last Saturday night, dismissed the dangerous Graham Napier (21) and David Masters within the space of two deliveries to confirm Warwcikshire's progress to the last four.

Trott and Clarke, who shared 113 for the third wicket, had earlier been central to the Warwickshire innings, with a late flourish from Peter McKay (22 off 13 balls) ensuring a competitive total, 20 coming from the final over.

Reece Topley was the pick of the Essex bowlers, taking 3-56, but it was not enough as his side exited the One-Day Cup at the quarter-final stage.

Man of the match Rikki Clarke told BBC Coventry & Warwickshire:

"Another great team performance. We always felt we were in control even when Jesse Ryder was going well and that we'd get them out if we stuck to our plans.

"It sounds a bit of a cliche, but we're just staying in the moment and trying to take one game at a time.

"We'll look to see who we get in the semi-finals but first we've got a very important Championship game coming up against Middlesex at Lord's."